Separators used to remove liquids and solids from gas streams typically comprise an elongated tubular vessel having a plurality of smaller and shorter tubular filter elements longitudinally disposed at one end of the vessel. This end of the vessel is closed by a removable head of typically the same diameter as the vessel to permit access to the filter elements so they may be removed and replaced from time to time as they become clogged with liquids and solids removed from the gas stream as it passes through the filters. The filter elements have closed forward ends adjacent the removable head and open rearward ends which communicate with flow path directive members and various chambers and ultimately with a discharge port. An inlet port admits the gas to be filtered which then may be directed through an inlet separation chamber or a tortuous flow path and ultimately to the outer surfaces of the filter elements. The gas then permeates the filter elements and flows through the rearward open ends to the discharge port.
The rearward open ends of the filter elements are usually mounted to respective fittings which have extending forwardly therefrom a spine or shank which extends centrally through the respective filter element to the forward end thereof. The forward end of the filter element is normally sealed by a cap which is mounted to the forward end of the shank. In one type of separator vessel, the filter elements are not spported upon a spine or shank, but are held in position by a rectangular matrix of bars which supports the forward ends which are secured by bolts and nuts to the bars. In servicing the vessel, the removable head is unscrewed and removed from the end of the vessel. Each filter element is then loosened at the forward end of the shank or at a supporting matrix and slid longitudinally forwardly through the end of the vessel.
Removal of the head is a difficult and time consuming task because of its size and weight. In commercial size units, the head may typically weigh several thousand pounds. Auxiliary closure hinges or davits are therefore required to aid in removal of the head. Further, the manufacture of such large heads (often 5 feet in diameter) is a very expensive step in the manufacturing process, and adds significant cost to the unit.
In present separator vessels, removal of the filter elements usually requires that the caps on the forward ends of each filter element be removed from the central shank extending through the filters, which is commonly done by unscrewing a nut from a threaded stud on the forward end of the shank. Upon installing the new filters, all of the forward ends thereof must be secured in the mounted position. Upon replacing the head on the end of the vessel, great care must be exercised to ensure a tight sealed fit, which is difficult and cumbersome. In the larger type vessels, a servicing operation typically requires a full work day.
Of considerable significance also are the changes involved in replacing filters which in large filter vessls require that a workman enter the vessel to remove and replace the filter elements. The liquids present in natural gas are usually flammable hydrocarbons which, if ignited by a spark, can seriously injure or kill the workman.